Exhibit 31.2 CERTIFICATION OF CHIEF FINANCIAL
OFFICER I, Ernest J.
Mrozek, certify that: 1. I have
reviewed this report on Form 10-Q of The ServiceMaster Company; 2. Based on my
knowledge, this report does not contain any untrue statement of a material fact
or omit to state a material fact necessary to make the statements made, in
light of the circumstances under which such statements were made, not
misleading with respect to the period covered by this report; 3. Based on my
knowledge, the financial statements, and other financial information included
in this report, fairly present in all material respects the financial
condition, results of operations and cash flows of the registrant as of, and
for, the periods presented in this report; 4. The
registrants other certifying officers and I are responsible for establishing
and maintaining disclosure controls and procedures (as defined in Exchange Act
Rules 13a-15(e) and 15d-15(e)) and
internal control over financial reporting (as defined in Exchange Act Rules
13a-15(f) and 15d-15(f)) for the registrant and have: (a) Designed
such disclosure controls and procedures, or caused such disclosure controls and
procedures to be designed under our supervision, to ensure that material
information relating to the registrant, including its consolidated
subsidiaries, is made known to us by others within those entities, particularly
during the period in which this report is being prepared; (b) Designed such internal control over financial reporting, or caused
such internal control over financial reporting to be designed under our
supervision, to provide reasonable assurance regarding the reliability of
financial reporting and the preparation of financial statements for external
purposes in accordance with generally accepted accounting principles; (c) Evaluated the effectiveness of the
registrants disclosure controls and procedures and presented in this report
our conclusions about the effectiveness of the disclosure controls and
procedures, as of the end of the period covered by this report based on such
evaluation; and (d) Disclosed in this report any change
in the registrants internal control over financial reporting that occurred
during the registrants most recent fiscal quarter (the registrants fourth
fiscal quarter in the case of an annual report) that has materially affected,
or is reasonably likely to materially affect, the registrants internal control
over financial reporting; and 5. The
registrants other certifying officers and I have disclosed, based on our most
recent evaluation of internal control over financial reporting, to the
registrants auditors and the audit committee of registrants board of
directors (or persons performing the equivalent functions): (a) All
significant deficiencies and material weaknesses in the design or operation of
internal control over financial reporting which are reasonably likely to
adversely affect the registrants ability to record, process, summarize and
report financial information; and (b) Any fraud,
whether or not material, that involves management or other employees who have a
significant role in the registrants internal control over financial reporting. Date: August
 9, 2007/s/ Ernest
 J. MrozekErnest J.
 MrozekVice
 Chairman and Chief Financial Officer 50